Fenestration. The placement of window openings in a building wall, one of the important elements in controlling the exterior appearance of a building. Also, a window, door, or skylight and its associated interior or exterior elements, such as shades or blinds.
Fiberglass. A composite material made by embedding glass fibers in a polymer matrix. May be used as a diffusing material in sheet form, or as a standard sash and frame element.
Fixed light. A pane of glass installed directly into non-operating framing members; also, the opening or space for a pane of glass in a non-operating frame.
Fixed panel. An inoperable panel of a sliding glass door or slider window.
Fixed window. A window with no operating sashes.
Flashing. Sheet metal or other material applied to seal and protect the joints formed by different materials or surfaces.
Float glass. Glass formed by a process of floating the material on a bed of molten metal. It produces a high-optical-quality glass with parallel surfaces, without polishing and grinding.
Fogging. A deposit of contamination left on the inside surface of a sealed insulating glass unit due to extremes of temperatures or failed seals.
Frame. The fixed frame of a window which holds the sash or casement as well as hardware.